Antitank mine



'Nava 15;, 1949 I c. H. MacFARLANb ANTITANK MINE Filed Oct. 17, 1945Patented Nov. 15, 1.949

UNITED STATES GFFICE Claims.

l The invention described herein may be manufactured and used by or forthe Government for governmental purposes without the payment to me ofany royalty thereon.

This invention relates to land mines.

A purpose of the invention is to provide a land mine the pressure plateof which will not be actuated by ground shock or air Waves resultingfrom explosions near the mine, but only by actual mechanical pressurefrom a passing vehicle or the like.

Another purpose of the invention is to provide a land mine which reducesthe tendency for dirt, and gravel to obstruct the efficient functioningof the mine.

A further purpose of the invention is to provide an improved land minewhich may be made of non-metallic materials.

Other purposes and advantages of the invention will become apparent fromthe following description of a preferred embodiment of the invention andwhich is illustrated in the accompanying drawings, in which:

Figure 1 is a plan view of the improved land mine, partly broken out;

Figure 2 is a fragmentary sectional view taken along line 2-2 of Figure1, and

Figure 3 is a fragmentary sectional view taken along line 3-3 of Figure1.

In the employment of explosive land mines intended for causing damagetoor for destruction of hostile vehicles such as tanks, armored cars,mobile artillery and materiel and personnel carriers, it has been foundthat explosion of a single mine in a mine neld may, by such effects assympathetic detonatlon or the force of the air set in motion by theexplosive blast, cause one or more nearby mines to explode.

Thus the sudden increase in air pressure may depress the pressure plateor spider on a nearby mine, causing it to explode and in turn possiblyexploding other mines, the result being the possible destruction of aWhole mine field or considerable portion thereof in consequence ofmerely exploding one mine in the iield. This invention is intended forpreventing the above mentioned explosion of nearby mines by depression0f their pressure plates or spiders as a result of a pressure wavecaused by explosion of a nearby mme.

To this end, means are provided whereby a relatively even pressure overthe surface of the pressure plate, such as may be caused by a suddenincrease in air pressure, will not set off the mine and in which it isnecessary for pressure to be amended April 30, 1928; 370 0. G. 757)applied to only a portion of the rim of the mine to actuate it.

As illustrated, the mine comprises a hollow casing or mine housing 2which is preferably made of a molded phenolic plastic material or othersuitable material. The housing 2 is closed at the bottom by a base disk4 which may be made of resin bonded plywood or other suitable material.As seen in Fig. 2, matching circular grooves 6 and 8, half-round incross section, are formed in the abutting surfaces of housing 2 and basedisk 4 and in the annular space formed when the matching grooves 6 and 8are aligned with each other is located an annular seal ring I0 made ofrubber or other suitable material for effecting a water-tight jointbetween members 2 and 4. The joint may also be cemented if desired.

A charge I2 of 'INT or other suitable high explosive material is locatedinside the mine in the explosive chamber I4 formed between the insidewall of casing 2 and the base disk 4. A booster charge I6 is located ina booster charge chamber I8 formed in and surrounded by the charge I2.The booster charge chamber I8 has a central opening 0r fuse chamber 20formed therein in which is disposed a mine fuse 22 having a cylindricalside wall 23 made of molded phenolic plastic material. The fuse 22 maybe a chemical type fuse of the kind in which a sealed glass or plasticvial or ampoule 24 containing liquid sulphuric acid is disposed above adry mixture 2E of potassium chlorate and sugar. When the vial 24 isbroken, the released acid flows to and comes in contact with the mixture26, causing it to burst into flame which ignites and explodes the heatsensitive explosive 28, located next to or just below the mixture 26 andwhich in turn explodes the surrounding annular shaped explosive boostercharge 3D. The resulting iiame and blast passes through vent holes 32formed in side wall 23, into contact with booster charge I6, explodingit and resulting in the explosion of the main TNT charge I2. Asillustrated, the charge 30 is annular in shape and has a central bore 34in which is disposed a cylindrical housing 36 rounded at its lower end31 and containing the mixture 2G and the explosive 28, all the mixturesand explosives being sufciently separated from each other by beingsurrounded by or enclosed in suitable materials such as are well knownin the art.

The fuse 22 is closed at its lower end by a hollow elongated plug 38which is threaded at 4I) into an annular base member 42 which in turn isthreaded at 44 into the lower end of the fuse side wall 23. The plug 38has a hollow upward projecting portion 46, closed at its upper end 48 sothat a cylindrical recess 50, threaded at 5| and open at the bottom 52is provided, and into which an anti-lift or pull type fuse may beinserted in any usual manner for causing the mine to explode if lifted.The members 38 and 42 are preferably made of plastic materialorother-'suitable nonmetallic material. Ase'alwasher isvlocate'dat53 asshown.

The fuse 22 is closed at its upper end by horizontal top wall 54 whichis thicker thanthe side walls of the fuse. A horizontal cylinfdricalrecess 56 is formed in top Walli541toreceivesthev ampoule 24, a plug 58being threaded into the open end of the recess 56 to closeitFeltpa'cking' 60 packed around the ampoule 24 serves to protect theampoule against breakage due to looseness in the recess 56.

The mine has a pressure platee Milformett" or" Y ceramic or plasticmaterial. The pressure plate B/Zfi'ssubstantially;icircularrirrplan Viewas shownin Figure 1, and has its central topvsurilacezrat: ask at V:Ii-4andrthef :remaining -rim portion formed with anfannularholmw depressioninrits:y upper surface as-at. @6eme-outer edgeff fof-.the rim. havingvits top :surface-09 j`coplianar` with theffcentralfsurface llt-fofwthe-Ypressrrrevplate. Asv best seen in :Figures-f 2 andtthe minfecasing;`2-has` an l annular upstanding elevatedyportion orbead; 'HIs upon whichis vsupportedtlfre.lowermost portion: of..- the: underside-of theAdepressed portion :66-V of the'. rim as atv 12. Itswill.L thusA 'benoted vthat downward pressure at-iany pointrorrthe outer. edge-iii!!VOff the. rimv asi-nA .theedirection ofsthe; arrow 'Mein Figure-f2; willbeznecessaryrvto-tiltethe pressure`v plate, in which vcase-the bead-'Nrwill servevas-the` fulcrum, andfthecentralportion.640iV the pressureplate will risessu'bstantiall-y in theedireetion of .the arrow.- Ss-howninFigure 2.:

To-cause pressure ornapoint :on the-rimasat- 'I4 .to breaktheglass-ampoule 24 thereby-liberating.v its contents and setting foi..the4 mine,v an.. ampoule breaking; member` T8; ispro-vided` as. shown inyligures -2 landpr Thesmember. '|8` has-rI an upper substantiallycylindrical uportion Illpand.- 4 a lower ring. ylike portion E'Z'as bestseen;finfl'igure.V 3,. the lower portion havingsa transverse aperturef84 therethrough, through `which. theampouIe. fllextends` and which,thusenci-'rcles .the ampoule;- with a l small amount. of; clearance.between the.. outer,A ampoule.. surface and lth'einner surface. ofi.'the hole 811i The topportion ofthefuse 22"? has an appropriate verticalaperture formed'.. therethrough to allowthe l'wer4 portionLZJto`extend'into Ithe hole 86 withcle'arancearound iti.. The Vuma-erportion. illfof ampoulebreaking" memloerVr "Is" extends through' aivertical. cylindrical' aperture 83 tnepressure plate, tne'faperture'8827 being enlarged' at 901'! A Y snap j ringLj9T'di'sp1sedj partly in'an annular peripheral' groove 94V on', portion 80'; servesVK tozpreventthe member' lifroml moving further downward :ntolole Vanolpitcl'f orother. sealingmateiial 'located in` tl"1"'e"1sur`4 j rounding space,serves botlras :a seal andY for-pre-` venting upward nrotioniofrr'ieihl'aer 8^`apartl fr'or'n'- the pressure plate., s,

As seen in Figures Zand vthe-pressureepl'ate has adownwardly?projecting.hollow cylilnzl'ricalll extension 98, largeenoughlin-insidediameterto. lit over` the upper.. portiorr 54. oftfuse-222.A with. adequate clearance,- `the extension-havingaexternailthreads ate-|001 Af-snfaplrsprin-ge|02srmade ofi phenolic plastick or"other suitable? materiah. has@ a. central hollow cylindrical portion or:hub |041' plate. The snap spring 02 also has six spaced ngers |06radiating from its cylindrical hub |04 as best seen in Figures 1 and 2,the distal ends |08 of the ngers |06 being receivable in an annularnotch ||0 formed in the upper surface of casing 2 under the inner side1I of bead |0 as shown in Figure Toyallfow-the six radiating. fingersA|06`f of the spring |02 to enter the notch ||0, the overhanging portion|I of the bead l0 is cut away as shown in Figure 3 at six correspondingspaced intervals indicated at 2 in Figure 1, thus leaving theoverhanging. portions of the bead 10 only between the six cut awayintervals |2. Thus, t0

riallowfthefradratingngers |06 to get beneath the overhanging portions1|, the entire spring is first" placed with the ngers |06 in registrywith thecutoutfintervals'l|2 and allowed to drop into the notch|=|10aseseen clearly in Figure 3. Then the spring |02 is given aone-twelfth revolution wherebyJ eacla. springA ringer.4 |06 isthusrotated from alocatiorrfl [2-to a location. II-ltobringita distal.endf-|08 loen'eatliv an overhanging. portonf '|I of the bead '|0Aas invFigure 2,..thus retaining.;A

. the end lofeeach springnger'llllinthenotch cannot take anypermanentset. The snapacti'on" Llargev clearance hole is' provi'ded"'i'r the'yoke'soi' nopload-whatever is puton the ampouletuntil'i the snapfspring:releases; This'means thatvl theV load 'required 'to"break theampoule.need not" bev` considered. in computin'gj the` rim load1 at which" theYmineA operates; Phen'olicwmaterial laminated with kraftf paper is*recommended as'suitable for* use in makingthe spring' 025 Y e Acylindrical rubber sealingA bellows I has* annular beads` ||8 and`|2'0"'adapter?f'or-loieine snapped Afinto-correspohd'i ngannularfgrooves: |22

10, the holes vbeingjspar-:ed byIzodegre'esfromr ,each other and.locatedN within the" pjortionsf I2 of the bead 'I' YCorrespondingjunthreaded"holes-' I 30"' are' formed/through'.the'abutting depressed portion ofthe'pressureplatel' Whenthe holesf* arein registry with .thejholes v|28;tlil'lrnlrscrewsi'i preventing the;pressure.; plate" from tilting and 'j ezq'aIc'ding.the'mine-v To armithe mine it' ispnlyii necessary to remove the thumb' screws |321 For,nal assembly, ,the fuse. assembly. isfrst consisting,V ofthee chemicalfuse.

assembled, boosterpellet, primer mixture, upper aridlower-vdetori-atorvclfrarges; andampoule. LW all moan-tedI ff threaded: to: thef extension 98 eY or: the: pressure? 751 inthe plslfisylndel'f threadedatf thefbtiiomf;

end as already explained, and the yoke 18, fitting loosely over thecenter of the ampoule in the slot 88 at the top end of the plasticcylinder. The fuse assembly is inserted into the proper cavity in thebody portion and xed in place by turning up the bottom center plug 38.This plug contains a cavity into which an anti-lift fuse may be insertedin the usual manner.

The next step is to place the top sub-assembly comprising the pressureplate and snap spring over the mine casing, centered so that the fingers|06 of the plastic spring will drop down to the level of the notch Hi8,being in positions H2.

VVThe top sub-assembly is thenrrotated one-twelfth of a turn to bringthe spring fingers E05 into positions H4. This also results in aligningthe thumb screw holes for insertion of the thumb screws.

Sealing of the mine is next accomplished by snapping the rubber sealbellows IE5 into positions as shown in Figure 2. The iinal operationConsists of installing the snap ring 92 over the top of the yoke intogroove 94, and sealing the snap ring by filling the cavity around itwith a plastic sealing compound.

While a preferred embodiment of the invention has been described inspecific terms, it is to be understood that numerous changes may be madein the size, shape, materials, and arrangement without departing fromthe spirit and scope of the invention.

I claim:

1. A land mine comprising a hollow casing, an explosive charge in saidcasing, an annular upstanding ring carried on said casing, a circularpressure plate supported on said ring concentrically therewith, saidplate having a substantially greater diameter than the ring, wherebyunbalanced pressure on the thus overhanging rim of said pressure platewill cause the plate to pivot on the ring as a fulcrum thus elevatingthe center of the pressure plate, an annular hub concentrically securedto said pressure plate, a plurality of substantially arcuate spring armsradiating from said hub, interlocking means between the free ends ofsaid spring arms and said annular upstanding ring, and primer meansresponsive to upward movement of any portion of the plate for ignitingsaid explosive charge, said spring arms initially resisting such upwardmovement of the plate and then suddenly releasing such resistance uponsaid spring arms reaching a predetermined degree of stress.

2. In a land mine, a hollow casing having an external shape generally inthe form of a segment oi a sphere and having a normally vertical centralaxis, an upstanding ring xed on said casing externally thereof andconcentric of said axis, said ring being formed to provide a pluralityof crcumferentially-spaced inwardly-facing notches about the peripherythereof, a circular pressure plate of greater diameter than said ring,means securing said pressure plate to said casing in position resting onsaid ring, said means comprising a Belleville-type spring centrallysecured to said pressure plate at the central under portion thereofV andhaving radial arms whose ends engage in respective ones of said notches,and means responsive to upward movement of the center of said pressureplate as a result of downward pressure upon the rim thereof, to detonatea fuse in said casing, said spring acting to resist the upward movementaforesaid.

3. A mine as recited in claim 2, the diameter of the base of said casingbeing approximately twice the diameter of said pressure plate.

4. A mine as recited in claim 2, and safety means comprising a pluralityof removable screws rigidly connecting said pressure Vplate to said ringat points circumferentially spaced about the periphery thereof.

5. A mine as recited in claim 2, said lastnamed means comprising anampoule mounted centrally in said casing closely adjacent said pressureplate, and a ring secured to said pressure plate centrally therebeneathand encircling said ampoule.

CHARLES H. MACFARLAND.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,539,609 Taylor May 26, 19252,336,701 Rasmussen Dec. 14, 1943 2,383,885 Parsons et al Aug. 28, 1945FOREIGN PATENTS Number Country Date 46,380 Sweden Jan. 14, 1920 864,354France 1941

